Coma and alteration of consciousness Flashcards
What is the definition of coma?
An unrousable state of unconsciousness.
What does consciousness depends on and therefore what causes loss of consciousness?
Consciousness depends on a working reticular activating system in the brain stem and the cerebral cortex. Coma arises from disturbance of these elements.
What are the 3 broad categories of causes of coma? What are some examples of each?
Infratentorial lesions that disrupt the reticular activating system directly.
- Infarct
- Haemorrhage
- Tumour
- Inflammatory lesion
Supratentorial lesions - large enough to cause herniation of to disrupt the cortex.
- subarachnoid haemorrhage
- extradural or subdural haematoma (raised ICP)
- Intracranial haemorrhage
- Tumour
- Infarct
Diffuse cerebral insult that affects the function of the cortex and reticular activation system.
- Metabolic (hypoglycaemia, hyperglycaemia, hyponatraemia, hypernatraemia, hypoxia, acidosis, hypothyroidism, hepatic failure)
- Toxic
- Drugs
- Alcohol
- Epilepsy
- Multiple sedative drugs
- Hypothermia
- Infections
- Meningitis/encephalitis
What are the differentials for coma with neck stiffness?
Meningitis, subarachnoid haemorrhage, foramen magnum herniation (rare).
What are the differentials for a coma with focal signs?
Infra- or supra-tentorial causes.
Tumour, inflammatory lesion, haemorrhage, infarct, SAH, extradural/subdural haematoma, intracranial haemorrhage.
What category of coma cause is a coma with no focal signs?
Diffuse cerebral lesions.
What 2 types of management are there?
Supportive treatments to all patients with a coma and specific treatment.
What supportive treatment is required in patients in a coma?
Maintaining blood pressure - fluids
Ventilation - protecting airways
Emptying stomach contents with nasogastric tube
TED stockings to avoid DVT
Maintaining homeostasis - blood gas and electrolytes.
Urinary catheterisation
Nursing with regular turning or use of air mattress to avoid pressure sores.
What is the management/treatment for a coma patient with fever and neck stiffness?
Broad-spectrum antibiotics to cover likely meningitis organisms.
Undertake a brain scan and if there is no contraindication, you perform lumbar puncture.
What is the management/treatment for a coma patient without fever but has neck stiffness?
Arrange a CT brain scan. If subarchnoid haemorrhage, treat. If no blood is seen or the scan is not diagnostic, proceed to lumbar puncture.
What is the management/treatment of a coma patient with focal signs and neck stiffness?
Cerebral imaging - might be foramen magnum herniation.
May need to reduce ICP with mannitol, dexamethasone, intubation and hyperventilation to reduce ICP.
Why should low sodium be corrected slowly?
To avoid complications such as central pontine myelinolysis.
What is used in encaphalitis for treatment?
Antiviral agents.
What is the treatment for opiate overdose?
Naloxone
What is the treatment for benzodiazepine overdose?
Flumazenil
